RE: Can ABS plastic be covered with fiberglass
You can make a mold from this with fiberglass IF you first cover this with a good thick layer of PVA. Use a good spraygun to apply a few layers of PVA until the entire surface is covered. Then let that dry overnight. The PVA will act as a barrier coat and prevent the gel you use to make the mold from melting the ABS. Heat could still be a problem, but if you let the gel cure fully then apply thin glass layers that cure fully before the next, you should not see temperatures above warm to the touch.
That said, you are going through alot of work to get a fiberglass hull that is probably not needed. If you were talking about a go fast planning hull I would say OK, but for a model of the African Queen, you are talking about a slow moving boat that is not going to be stressed out enough to worry about the hull being weakened and damaged by use. The ABS will last forever if the boat is not dropped or stressed beyond the normal operation of it.